As suggested, I looked up the accusation against Duane and this is what I found in a Rolling Stones interview with Dickey Betts:
In 1976, the Allmans broke up, Betts telling Rolling Stone, “There is no way we can work with Gregg again. Ever.” Gregg had testified in court against his drug dealer and road manager, which the bandmates saw as a betrayal.
As most of you know, they did work again until Betts was asked to leave the band.
Anyway - this show is great. I'm a big NRPS fan and their set from this time is also great. What a fun evening this must have been. Wished I was there.

To mr mind wondering Duane Allamann is not a narc! You sir need to look it up.It was his brother Greg that got in trouble and testified against his good friend Twigs . Duane wasnt even alive at that point when this went down.Perhaps if he was things would of went down different.
Great show wish Duane played more with the boys.However not even the best of the week.

Skipped by Ladies & Gentlemen (which has both the previous and next nights), this is the lesser show of the week. You might start with the 28th (else 27th). There is also a lot of out-of-tune on this show. Still, a couple highlights here are big ones. Duane Allman guests on three songs and his lead on Sugar Mag is probably what the show is known for (though it should be the Dawk Staw). He died just months later. Three songs from this show were used a base tracks for Skull Fuck, released later in the year. There used to be lots of missing sections/songs on the copies that circulated. Today there are three (or maybe four...) songs that DNC. All sources have speed wavers to some extent, and there are tape-flip gaps, with no AUDs for patch.
First Set. All sources are missing the best-of-all-time Bertha/Uncle opener! Just kidding - nobody knows. The songs mostly repeat all week but this was the only Big Boss Man, and though not best-of-tour, it's solid. It was used for Skull Fuck - with the harmonica solo replaced (though the original is better). Loser was played every night this week. This one's well-played, but OOT. The Hard to Handle on the 20th is one of the best ever; but I have warmed to this one, improving my opinion of the set. This Dawk Staw is possibly the best of the year. It's somewhat Billy/Phil-centric. Several parts are great, but one is where they speed up to get to the verse. So cool. It's been said this is the only DS played as a quartet, but that's Pig on shaker. I can see why they used this Wharf Rat for Skull Fuck, however the middle section on the album is a studio creation. Several vocal lines were replaced, Merl Saunders' organ was added, and Keith dubbed new piano. Also, it fades out when it doesn't need to - just seconds before a hard ending. The sound is poor for Casey Jones but there is some intricate playing.
Second Set. Duane Allman, having sat in on the NRPS set, joins for the first three. The band has to play pretty straightforward for Sugar Mag, but if you want to check out the dualing leads you can hear them much better on Skydog (apparently mixed from the multis). Allman leaves after a perfunctory Beat it On Down the Line-9. China>Rider has more OOT, and we only have the first half of the latter. The Mama Tried included on some sources is from Skull Fuck - the original went missing, though they might be the same. The rest is average '71 (when it's not OOT).
1st Set:  B-
2nd Set: C
Overall = 3 stars
Highlights:
Hard to Handle - warmed to this one
Dark Star - one of year's best
Mama Tried - the classic version (we assume)
SOURCES: Best is the miller_105814. Most other SBDs have varying pitch errors. This source also has the more complete Rider, though the channels are switched on the second set and some of the first (Loser, Playin; Wharf, Casey). [Parts of] three songs are on Skull Fuck. Sugar Magnolia is on Allman's Skydog: Retrospective.

This is actually the only show from the run at the Fillmore East that has no cuts included on Ladies and Gentlemen... The Grateful Dead.
Great week of shows. I was there.